In a boiler having a circulating fluidized bed, gas carrying particles such as ash, sand, coal, etc. is injected into the cyclone where it goes round the skirt which is a cylinder in the shape of a truncated cone. The gas is then rotated around the skirt and the particles fall to the bottom of the cyclone body, with the gas escaping via the skirt. The temperature inside the cyclone may reach about 900.degree. C., and the skirt may be about 4 meters in diameter and weigh up to about 4 tonnes (i.e. metric tons).
Currently, in certain dispositions, the cyclone skirt is simply placed via an annular flange on the shoulder which is formed at the top of the cyclone body and which is made of refractory material.
Due to the forces exerted on the skirt and to the high and possibly variable temperature prevailing in the cyclone, the skirt and in particular its support flange tend to be deformed, and the weight of the skirt is then no longer transmitted uniformly to the supporting refractory material. When thus subjected to too much force, the refractory material splits and then breaks, thereby bringing the skirt into a wrong position where it tilts, and, in extreme cases, even leading to the skirt falling off.
U.K. Patent G.B. 2 124 932 describes a cyclone skirt arrangement designed to solve the problems of dismounting the skirt and of deformation due to thermal stress. To this end, the skirt is divided into independent segments supported at their tops in detachable manner by parts welded to the wall of the cyclone or by direct bolting.
An object of the present invention is to solve these problems by providing an arrangement for both supporting and also guiding a one-piece skirt without the skirt being supported directly on the refractory material.